Re: [PATCH Part2 RFC v4 26/40] KVM: SVM: Add KVM_SEV_SNP_LAUNCH_FINISH command

[Sean Christopherson]

On Wed, Jul 07, 2021, Brijesh Singh wrote:
> +        struct kvm_sev_snp_launch_finish {
> +                __u64 id_block_uaddr;
> +                __u64 id_auth_uaddr;
> +                __u8 id_block_en;
> +                __u8 auth_key_en;
> +                __u8 host_data[32];

Pad this one too?

> +        };
> +
> +
> +See SEV-SNP specification for further details on launch finish input parameters.

...

> +	data->gctx_paddr = __psp_pa(sev->snp_context);
> +	ret = sev_issue_cmd(kvm, SEV_CMD_SNP_LAUNCH_FINISH, data, &argp->error);

Shouldn't KVM unwind everything it did if LAUNCH_FINISH fails?  And if that's
not possible, take steps to make the VM unusable?

> +
> +	kfree(id_auth);
> +
> +e_free_id_block:
> +	kfree(id_block);
> +
> +e_free:
> +	kfree(data);
> +
> +	return ret;
> +}
> +

...

> @@ -2346,8 +2454,25 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu)
>  
>  	if (vcpu->arch.guest_state_protected)
>  		sev_flush_guest_memory(svm, svm->vmsa, PAGE_SIZE);
> +
> +	/*
> +	 * If its an SNP guest, then VMSA was added in the RMP entry as a guest owned page.
> +	 * Transition the page to hyperivosr state before releasing it back to the system.

"hyperivosr" typo.  And please wrap at 80 chars.

> +	 */
> +	if (sev_snp_guest(vcpu->kvm)) {
> +		struct rmpupdate e = {};
> +		int rc;
> +
> +		rc = rmpupdate(virt_to_page(svm->vmsa), &e);

So why does this not need to go through snp_page_reclaim()?

> +		if (rc) {
> +			pr_err("Failed to release SNP guest VMSA page (rc %d), leaking it\n", rc);

Seems like a WARN would be simpler.  But the more I see the rmpupdate(..., {0})
pattern, the more I believe that nuking an RMP entry needs a dedicated helper.

> +			goto skip_vmsa_free;